A modified Zerilli–Armstrong constitutive model for simulating severe plastic deformation of a steel alloy

Author(s):  
Muralimohan Gurusamy ◽  
Balkrishna C Rao

A modified Zerilli–Armstrong model has been proposed and validated in previous works for simulating distinct deformation mechanisms of continuous-shear and shear-localization during severe plastic deformation of a face centered cubic alloy. In this paper, the validity of the modified Zerilli–Armstrong model has been further tested by using it for modeling the severe plastic deformation of another face centered cubic material, a steel alloy. In particular, the modified Zerilli–Armstrong model is used as a constitutive relation for simulating behavior of AISI 1045 steel alloy while undergoing severe plastic deformation through orthogonal and plane-strain machining. Accordingly, the performance of the constitutive relation in predicting flow stress distribution along the primary shear zone is validated by comparing with forecasts made using the distributed primary zone deformation, the original Zerilli-Armstrong and Johnson-Cook models. Furthermore, finite element simulations of orthogonal cutting of this steel alloy were carried out, and good agreement was observed between the predicted chip morphology and attendant cutting forces with experimental values reported in literature for a range of cutting conditions. The force predictions also fared better compared to those predicted by using the Zerilli-Armstrong and Johnson-Cook models. These validations provide further corroboration of using the modified Zerilli–Armstrong model as a constitutive relation for simulating the behavior of face-centered cubic materials under conditions of high plastic strains and also high strain-rates.

Author(s):  
Hongtao Ding ◽  
Yung C. Shin

Materials often behave in a complicated manner involving deeply coupled effects among stress/stain, temperature, and microstructure during a machining process. This paper is concerned with prediction of the phase change effect on orthogonal cutting of American Iron and Steel Institute (AISI) 1045 steel based on a true metallo-thermomechanical coupled analysis. A metallo-thermomechanical coupled material model is developed and a finite element model (FEM) is used to solve the evolution of phase constituents, cutting temperature, chip morphology, and cutting force simultaneously using abaqus. The model validity is assessed using the experimental data for orthogonal cutting of AISI 1045 steel under various conditions, with cutting speeds ranging from 198 to 879 m/min, feeds from 0.1 to 0.3 mm, and tool rake angles from −7 deg to 5 deg. A good agreement is achieved in chip formation, cutting force, and cutting temperature between the model predictions and the experimental data.


2010 ◽  
Vol 667-669 ◽  
pp. 355-360
Author(s):  
Petra Šedá ◽  
Aleš Jäger ◽  
Pavel Lejček

Equal channel angular pressing (ECAP) is a promising severe plastic deformation technique for production of ultrafine-grained bulk metals with face centered cubic (fcc) structure. However, the process is often complicated in hexagonal close packed (hcp) metals such as magnesium due to its low forming capability. In this contribution, magnesium single crystals were processed by ECAP through a single pass in order to reveal processes taking place in hcp lattice during severe plastic deformation. The microstructure and texture were investigated by SEM-EBSD. The deformed microstructure contains shear bands, recrystallized regions and mechanical twins. Activity of twinning systems and texture formation are discussed regarding different initial orientation of the single crystals.


Author(s):  
Hongtao Ding ◽  
Yung C. Shin

Materials often behave in a complicated manner involving deeply coupled effects among stress/stain, temperature and microstructure during a machining process. This paper is concerned with prediction of the phase change effect on orthogonal cutting of AISI 1045 steel based on a true metallo-thermo-mechanical coupled analysis. A metallo-thermo-mechanical coupled material model is developed, and a finite element model is used to solve the evolution of phase constituents, cutting temperature, chip morphology, and cutting force simultaneously using ABAQUS. The model validity is assessed using the experimental data for orthogonal cutting of AISI 1045 steel under various conditions, with cutting speeds ranging from 198 to 879 m/min, feeds from 0.1 to 0.3 mm, and tool rake angles from −7° to 5°. A good agreement is achieved in chip formation, cutting force and cutting temperature between the model predictions and the experimental data.


Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 284 ◽  
Author(s):  
Jinqiang Ning ◽  
Steven Liang

Elevated temperature in the machining process is detrimental to cutting tools—a result of the effect of thermal softening and material diffusion. Material diffusion also deteriorates the quality of the machined part. Measuring or predicting machining temperatures is important for the optimization of the machining process, but experimental temperature measurement is difficult and inconvenient because of the complex contact phenomena between tools and workpieces, and because of restricted accessibility during the machining process. This paper presents an original analytical model for fast prediction of machining temperatures at two deformation zones in orthogonal cutting, namely the primary shear zone and the tool–chip interface. Temperatures were predicted based on a correlation between force and temperature using the mechanics of the cutting process and material constitutive relation. Minimization of the differences between calculated material flow stresses using a mechanics model and a constitutive model yielded an estimate of machining temperatures. Experimental forces, cutting condition parameters, and constitutive model constants were inputs, while machining forces were easily measurable by a piezoelectric dynamometer. Machining temperatures of AISI 1045 steel were predicted under various cutting conditions to demonstrate the predictive capability of each presented model. Close agreements were observed by verifying them against documented values in the literature. The influence of model inputs and computational efficiency were further investigated. The presented model has high computational efficiency that allows real-time prediction and low experimental complexity, considering the easily measurable input variables.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5834
Author(s):  
Chi Zhang ◽  
Laszlo S. Toth

During severe plastic deformation (SPD), there is usually extended grain fragmentation, associated with the formation of a crystallographic texture. The effect of texture evolution is, however, coarsening in grain size, as neighbor grains might coalesce into one grain by approaching the same ideal orientation. This work investigates the texture-induced grain coarsening effect in face-centered cubic polycrystals during simple shear, in 3D topology. The 3D polycrystal aggregate was constructed using a cellular automaton model with periodic boundary conditions. The grains constituting the polycrystal were assigned to orientations, which were updated using the Taylor polycrystal plasticity approach. At the end of plastic straining, a grain detection procedure (similar to the one in electron backscatter diffraction, but in 3D) was applied to detect if the orientation difference between neighboring grains decreased below a small critical value (5°). Three types of initial textures were considered in the simulations: shear texture, random texture, and cube-type texture. The most affected case was the further shearing of an initially already shear texture: nearly 40% of the initial volume was concerned by the coalescence effect at a shear strain of 4. The coarsening was less in the initial random texture (~30%) and the smallest in the cube-type texture (~20%). The number of neighboring grains coalescing into one grain went up to 12. It is concluded that the texture-induced coarsening effect in SPD processing cannot be ignored and should be taken into account in the grain fragmentation process.


2011 ◽  
Vol 223 ◽  
pp. 286-295 ◽  
Author(s):  
Cédric Courbon ◽  
Tarek Mabrouki ◽  
Joël Rech ◽  
Denis Mazuyer ◽  
Enrico D'Eramo

The present work proposes to enhance the thermal interface denition in Finite Element (FE) simulations of machining. A user subroutine has been developed in Abaqus/Explicit © to implement a new experimentally-based heat partition model extracted from tribological tests. A 2D Arbitrary-Lagragian-Eulerian (ALE) approach is employed to simulate dry orthogonal cutting of AISI 1045 steel with coated carbide inserts. Simulation results are compared to experimental ones over a whole range of cutting speeds and feed rates in terms of average cutting forces, chip thickness, tool chip contact length and heat flux. This study emphasizes that heat transfer and temperature distribution in the cutting tool are drastically in uenced by the thermal formulation used at the interface. Consistency of the numerical results such as heat flux transmitted to the tool, peak temperature as well as hot spot location can be denitively improved.


2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Ehsan Etemadi ◽  
Jamal Zamani ◽  
Alessandro Francesconi ◽  
Mohammad V. Mousavi ◽  
Cinzia Giacomuzzo

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